Borehole image log analysis

 

Borehole image QC and processing

The QC of your image and related data is an essential step to build confidence in any interpretation carried out on the image. At ImageStrat we carry out a range of QC procedures, make corrections where necessary, and communicate our findings to you.


Get in touch to talk about the QC of your data.

Structural interpretation of borehole images

Once your image is built we can identify features in your image that can be used to investigate the geological structure of your formation. We also identify faults, fractures, borehole breakout, and drilling-induced tension fractures to help you understand your deformation history and modern stress regime.


Get in touch to talk about structural interpretation with us.

Sedimentological interpretation of borehole images

At ImageStrat we work out your ImageStratigraphy. We can zone your well by identifying facies, facies associations and relate these to palaeodepositional environments through comparison to published studies of modern and ancient depositional systems. Borehole images also provide dip and dip azimuth of sedimentary surfaces so we can help you with palaeogeographic reconstructions.


Get in touch to talk about sedimentological interpretation of borehole images.

Advanced borehole image analysis

We offer a range of bespoke analyses. Please get in touch to find out how we can help.

Geomechanics

In addition to your image analysis results, you may wish to consider the following geomechanics services. If you are interested, please contact us at geomechanics@imagestrat.com so that we can provide more details and an indicative price.

 

Basic geomechanics image analysis

We provide a preliminary interpretation of features of geomechanical interest, specifically drilling-induced tension fractures (DITF) and borehole breakout (BO), as visible in your images. We carefully check and QC the image data to differentiate DITF and BO from other features such as natural fractures and washout. We provide the basic interpretation of the orientations and approximate magnitudes of the in-situ stresses.

Vertical stress, pore pressure, and fracture gradient

Building on the image analysis results, we add the calculation of the overburden or vertical stress, and estimates of the formation fluid pressure and fracture gradient. We include analysis of the critical log data (density, sonic, and resistivity) and include analysis of the drilling experiences (from daily drilling reports) and also any formation pressure measurements and formation integrity tests (FIT) or leak-off tests (LOT). The constrained estimates of the vertical stress, formation pore pressure, and fracture gradient can then be used for the design and planning of additional wells (including casing points and operating mud weights), and for consideration in the advantageous siting of development infrastructure.

Full geomechanical model including the in-situ stress tensor, pore pressure, and rock strength estimates

Building onwards from the vertical stress, pore pressure, and fracture gradient results, we develop estimates of the rock strength and of the maximum horizontal principal stress. Typically this is done using the observed breakout (BO) and drilling induced tensile fracture (DITF) coupled with inferred or measured rock strength data. The result of this module is a full estimate of the stress tensor, the fluid pressure, and the rock strength, all as a function of depth. These estimates are typically checked and constrained by comparison to the observed drilling experiences. The results are then used in three main areas, namely 1) wellbore stability analysis and well planning, 2) analysis of critically stressed fractures and faults, and 3) siting of infrastructure and development.

Wellbore planning and stability prediction

With a complete geomechanical model, we then produce estimates or recommendations on the safe mud weight window for a future well in the same project area. Your proposed well trajectory and casing points are checked against the predicted breakout widths, the inferred fracture gradient, and the inferred pore pressure, in order to minimise the risk of lost drilling time events such as kicks, lost circulation, tight hole, stuck pipe, and loss of drilling strings or logging tools.

Critically stressed fracture analysis

The geomechanical model is convolved with known or inferred fracture orientations to determine which fracture orientations are most likely to be critically stressed, and thus subject to small shear movements. These movements are typically associated with opening or fluid migration, which can be of great help in enhancing flow into the wellbore during production, or conversely controlling or avoiding early water cut. Some aspects of the critically stressed fracture analysis can be useful input for choice of completion methods.

Core-based services

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Core description

Full core description at wellsite, core store, or office.

Sidewall core description

Full description of sidewall cores.

Grain size analysis

Grain size analysis of thin sections, sidewall cores, or core.

 

Contact Us

0473 538 899

 

1131 Hay Street, West Perth, WA 6005, Australia

ABN: 83 628 178 709
ACN: 628 178 709

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